Expect to do a double-take or two when you see Mark Wahlberg in "The Gambler," director Rupert Wyatt's crime drama based on the 1974 film of the same name.

Usually known for his imposing presence and endless muscles, Wahlberg took a cue from his "The Fighter" co-star Christian Bale for the role of literary professor-by-day, gambler-by-night Jim Bennett, dropping a ton of weight to disappear into his character.

At first, Wahlberg wanted to go the opposite direction. "It was like, 'Why not just do the weight gain thing? Eat a few pounds of cheeseburgers and beer, and look like a real teacher," he joked with MTV. But Wahlberg said that Wyatt had a specific vision in mind for the character, which required Wahlberg to shed some pounds.

Once he started losing weight, Wahlberg became obsessed with the process. "Right around the start of shooting, they said, 'You're good, you're good, don't lose anymore weight,'" he said. "And I just kept going until the last day. I was like, 'Well, in "Boogie Nights," I was 138 pounds, so I have to beat that.' And the tailor was knocking on my door every day to tighten up my suit, pants and jacket."

Wahlberg said that the lack of food and rapid weight loss helped him focus even more on the task at hand, and wasn't even the hardest part of shooting "The Gambler." (That distinction belongs to "being confident as a literary professor," which is why he always carried around a dictionary.) In fact, the Oscar-nominated star, now back in full muscular form, said he could see himself dropping weight again.

"If you had asked me right after the movie, I'd say, 'Never again,'" he said. "But you forget [what it was like] as time goes on, and if the right thing comes along…"